Despite multiple initiatives in the VA healthcare system, at least 30% of the estimated three million Veterans with hypertension do not reach the current target blood pressure (BP). Hypertension induces pathological remodeling of the vascular wall, leading to further increases in BP and end organ dysfunction. These effects are linked to 5,000 annual deaths among Veterans. Emerging data suggest that mitochondrial ROS production is a common denominator in hypertension, but mechanistic concepts of how mitochondrial function in VSMC drives hypertension and remodeling are missing. Our group has made significant contributions to unraveling the function of the multifunctional Ca2+/calmodulin-dependent kinase II (CaMKII) in the vasculature in vivo and defined previously unrecognized pathways by which CaMKII controls VSMC Ca2+ handling, remodeling and BP. Of note, CaMKII is present in mitochondria and believed to control mitochondrial matrix Ca2+ influx via the mitochondrial Ca2+ uniporter. We recently made the novel discovery that inhibition of CaMKII in VSMC is sufficient to block mitochondrial ROS production and prevent Angiotensin-II (Ang-II) hypertension. Our long-term goal is to help develop selective CaMKII inhibitors that can be used clinically for the treatment of hypertension. As a next step toward this goal, the objective of this application is to delineate the function of CaMKII in hypertension-induced mitochondrial dysfunction. Here we propose to test the novel and innovative hypothesis that CaMKII contributes to a ROS-generating, pro- hypertensive feed forward circuit in vascular smooth muscle by actions in mitochondria. We have developed new genetic mouse models where we can conditionally and selectively control mitochondrial CaMKII in VSMC, which will be used to test the following three specific aims: 1) Dissect the molecular pathways by which mitoCaMKII controls mitochondrial function and mitoROS production in VSMC. 2) Dissect the mechanisms by which mitoCaMKII inhibition in VSMC protects against vascular wall remodeling and hypertension by Ang-II. 3) Establish the therapeutic potential of mitoCaMKII inhibition in a model of chronic hypertension. Aim 1 will provide the cellular mechanisms through which CaMKII controls mitochondrial function. Data from aim 2 will determine pathways by which mitochondrial CaMKII in VSMC drives BP increases through mitochondrial ROS, whereas aim 3 will directly test whether mitochondrial CaMKII inhibition in VSMC can be used as treatment in hypertension. The approach is innovative because of its use of novel in vivo models and specific tools to dissect mitochondrial function. The proposed research is significant because it is expected to advance the field by defining a novel molecular target for antihypertensive therapy. Ultimately, such knowledge may allow for the development of new therapeutic strategies in hypertension that will benefits our Veterans.